winter fish below thermocline

[jimmyjoe]

   DNR drained a 187 acre lake near me in Iowa. They're renovating it. The upper 1/3 is shallow from siltation, but the lower 2/3 is 30 to (ultimately) 50+ feet deep. I saw a person putting PEX "trees" out on the lake bottom, where the 30-foot depth begins. (PEX pieces were leftovers.) I asked him why he did that  when the lake was known for having a thermocline no deeper than 16 feet in summer.

   He said that in spring, from the time turnover occurs (Probably mid-April) until the thermocline actually forms (he thought about late June) the bass will occupy any depth, only moving up after the thermocline forms. And he thought that the fish will inhabit this depth in winter anyway, and that they'd benefit from artificial habitat.

  

   I don't know what to think about this. Some questions:

 

   1) If the lower 1/3 of the lake is around 50 feet and the middle is 30 feet, won't wintering bass gravitate to the deepest areas?

   2) Do overwintering bass benefit from cover, artificial or otherwise?

   3) I always thought that as soon after spring turnover as possible, fish move into shallow (5-20 feet) water because they need to eat, and that's where the food is.

   4) I thought the food was at this level because light was strongest at this level.

   5) I always thought that there was little plant growth below 20 feet because light was limited, which limited the growth of forage fish.

 

    Am I wrong about these things?        jj

[WRB]

Shouldn't be a thermocline in the cold water period or winter. The fall tournover mixes the water column eliminating the warm water period thermal layers. Lake that freeze can experience a ice out turnover with the heavy surface water mixing the lower warmer  water.

Tom

 

[jimmyjoe]

11 minutes ago, WRB said:

Shouldn't be a thermocline in the cold water period or winter. The fall tournover mixes the water column eliminating the warm water period thermal layers. Lake that freeze can experience a ice out turnover with the heavy surface water mixing the lower warmer  water.

Tom

 

   Correct. That's why I said that the lake had a 16-foot thermocline in summer, and why I said that the thermocline formed sometime in June.  I guess I didn't clarify that enough.   jj

[WRB]

I didn't take the time to read though your post.

Tom

[jimmyjoe]

8 minutes ago, WRB said:

I didn't take the time to read though your post.

Tom

   S'okay.   ?    jj

[Dens228]

I can only tell you that in a quarry I fish a lot I've caught my two biggest bass there in the early spring in 22-24 feet of water.  They were at the bottom of a steep drop off and there is cover in the form of vegetation.  This vegetation gets quite thick in the summer. But it also has structure in the drop off.  Now the water in this quarry is VERY clear.  

 

I can also tell you that the thermocline in this quarry varies between about 14-16 feet in the summer and I have NEVER caught or marked bass on my FF below the thermocline. 

[jimmyjoe]

18 minutes ago, Dens228 said:

I can only tell you that in a quarry I fish a lot I've caught my two biggest bass there in the early spring in 22-24 feet of water.  They were at the bottom of a steep drop off and there is cover in the form of vegetation.  This vegetation gets quite thick in the summer. But it also has structure in the drop off.  Now the water in this quarry is VERY clear.  

 

I can also tell you that the thermocline in this quarry varies between about 14-16 feet in the summer and I have NEVER caught or marked bass on my FF below the thermocline. 

   Well, that pretty well jibes with what this guy said. I guess a brand-new window just opened up for me, a window about 2 months long. This principle applies to two other lakes close to me, too. 

   Looks like Jimmy's gonna have fun come spring!   Thnx.     jj

  

[Catt]

Just a dumb Cajun's opinion  ?

 

It is my understanding turn over occurs in the fall.

 

Bass do migrate "deep" during winter but not necessarily the deepest water in the lake.

 

There is a lot of plant growth below 20'.

 

Thanks! I gonna be mulling over this thread all day!

[scaleface]

I cant  answer because I dont know . In a small lake i fish often the max depth is 30 foot . During the summer the thermocline usually sets up around 15 to 20 foot . This past November when the thermocline was gone and water temp at 42 degrees I caught  bass at 25 foot. The deepest I ever caught them from this lake . One year at Mark Twain lake ,late in the fall , I caught them at 40 foot which is a lot deeper than the summertime thermocline which is usually 12 to 25 foot . Water clarity has a big influence and the water is often clearer during the winter .

[jimmyjoe]

1 hour ago, Catt said:

Bass do migrate "deep" during winter but not necessarily the deepest water in the lake.

 

There is a lot of plant growth below 20'.

   This agrees also with what the guy said.

  

   I guess my idea of what went on in a small lake during winter and early spring was way too simple. (Can I blame that on river fishing all those years?)  Especially, I had no idea that there were freshwater plants that thrived in deep water. Articles like this   https://www.lakeaccess.org/ecology/lakeecologyprim9.html

that has this sentence, " .... In most lakes, the sunlit euphotic zone occurs within the epilimnion. ...." led me to think that way.

    However, that same article cites examples of deep plant life in clear-water lakes that are, I admit, much larger than the little lake I'm talking about.

 

   So here's what I thought happened in spring:

   Before the spring turnover (or remix) bass are deep and lethargic. When the spring remix occurs, I thought bass went hell-bent for shallower water because the sun warmed the water and because the sun caused an explosion of plant growth. I guess I never stopped to think just what was meant by "shallower".

    I thought it was all about light, warmth and oxygen. And it is .... but differently than I had thought.

 

    So here is (evidently) what happens in spring:

    When the spring remix occurs, a lake has oxygen over a huge range of depths until the thermocline forms. And that can take months. During this time, I guess the bass bite at all depths, and they can move to (and feed at)  any depth they want, kinda like hit-and-run guerilla warfare.

    I had always fished shallow-only in spring. Looks like I was wrong.   

   

    If you just live long enough, you can learn new stuff!   ??    jj

 

  

   

   

  

[dgkasper58]

12 minutes ago, jimmyjoe said:

   This agrees also with what the guy said.

  

   I guess my idea of what went on in a small lake during winter and early spring was way too simple. (Can I blame that on river fishing all those years?)  Especially, I had no idea that there were freshwater plants that thrived in deep water. Articles like this   https://www.lakeaccess.org/ecology/lakeecologyprim9.html

that has this sentence, " .... In most lakes, the sunlit euphotic zone occurs within the epilimnion. ...." led me to think that way.

    However, that same article cites examples of deep plant life in clear-water lakes that are, I admit, much larger than the little lake I'm talking about.

 

   So here's what I thought happened in spring:

   Before the spring turnover (or remix) bass are deep and lethargic. When the spring remix occurs, I thought bass went hell-bent for shallower water because the sun warmed the water and because the sun caused an explosion of plant growth. I guess I never stopped to think just what was meant by "shallower".

    I thought it was all about light, warmth and oxygen. And it is .... but differently than I had thought.

 

    So here is (evidently) what happens in spring:

    When the spring remix occurs, a lake has oxygen over a huge range of depths until the thermocline forms. And that can take months. During this time, I guess the bass bite at all depths, and they can move to (and feed at)  any depth they want, kinda like hit-and-run guerilla warfare.

    I had always fished shallow-only in spring. Looks like I was wrong.   

   

    If you just live long enough, you can learn new stuff!   ??    jj

 

  

   

   

  

I would add that the Bass will go where the bait is.  I have caught bass while ice fishing in 12' water when there were 40' holes around as every fish is not in the deepest part (I kind of wish this was the way it was).  If the fish can tolerate the temperature/oxygen level and a food source is near they can survive just fine.

[Glenn]

Ok, let's clarify a few things.

 

First off, bass follow the baitfish.  That's their food source.  So that's a primary factor that determines their depth, and what structure/cover they're using. Baitfish are more affected by colder water temps than bass. Some baitfish struggle to survive as the water continues to drop below 50.  It's usually warmer in deeper water, so that's where the baitfish head, and the bass follow.  However, there's less cover available for them to hide, so predation is higher. So as temps begin to warm up in Spring, the baitfish head for shallower cover asap for protection, and the bass follow.  At the same time, bass need to feed up for the spawn, so you'll find greater populations of aggressive bass shallow in spring.

 

Second, these are not absolute "rules". Brief warming periods during winter may drive baitfish shallow, seeking protective cover, and the bass will follow.  So it is possible to catch bass shallow at times, even in the dead of winter.

 

Third, Spring "turnover" isn't a widespread thing, and only happens if the pond/lake is frozen. That's not to say every frozen lake experiences Spring turnover.  Again, it's not a common occurrence.  So I wouldn't consider it.

 

Fourth, keep in mind fish can't survive very long below the thermocline due to lack of oxygen, but it's not instant death. Bass will endure short stints beneath the thermocline if that's where they chase the baitfish.  So you'll probably get a few people that tell you they've caught fish below the thermocline. It can happen.

 

Fifth, summer thermoclines don't always occur every year, even in the same lake where it happened the previous year.  And the depth where it occurs can vary greatly. 

 

Sixth, the depth of plant growth is primarily determined by light penetration. As a general rule, the clearer the water, the deeper aquatic vegetation will grow.  Your mileage may vary depending on available nutrients, bottom composition, and type of plants.  But vegetation in 20' or deeper is not uncommon in clear ponds and lakes.

 

Hope that helps!

 

 

[jimmyjoe]

   Yes, that explains perfectly why this worker was putting habitat at the 30' level.

   Thnx.    jj

 

p.s.   I didn't realize #s 3 and 5 were so variable. You just made me work harder!   ??   jj

[WRB]

Bass can't read!

The bass calendar doesn't have spring, it has winter cold water period, the spawn cycle in 3 cycles; pre spawn-spawn-post spawn, summer warm water period ( thermoclines develope in most lakes) and fall.

The most productive period to catch big bass is pre spawn as they feed more often to get ready to fast during and the spawn egg laying cycle. How deep are pre spawn bass depends on the lakes forage base. Where I fish the bass are anywhere from 1' to 60' during the cold water winter period and catchable throughout the water column.

Pre Spawn the bass move up to where the majority of prey is concentrated. Crawdads are becoming more availble, larger prey fish are also moving more for their spawn cycles and big bass take advantage. My top 5 giant bass were all caught on jigs in 20'-15' of water where the crawdads were abundant. 

Hatchuary raised rainbow trout are planted during the cold water period until it reaches 60 degrees and the big bass feed on them during that time period. Swimbait bass are caught anywhere from the surface to 60' primarily during the trout planting time period.

When the summer thermocline sets up around mid summer the big bass hang around that depth because the hold over trout are located at that depth when availble. 

Summer warm water period the bass have a lot of prey sources.

Tom

PS, most green aquatic plants can't grow deeper then the depth of sunlight.

  

[jimmyjoe]

3 minutes ago, WRB said:

. Where I fish the bass are anywhere from 1' to 60' during the cold water winter period and catchable throughout the water column.

   Man, I am SO jealous of all you fishermen who can fish in the winter! Winter fishing around here is ice fishing. There have been some winters around here when people drove their pickups out on the ice and bored holes. It's not like Minnesota around here, and it's not consistent, but so far every winter has supported some kind of ice fishing. Not by me, mind you, but by others. I'm chicken.

   Spring fishing in areas like this is a little different than spring fishing in areas that don't freeze. Just not quite as different as I had thought. I see that now.

  

    C'mon, SPRING!!!         jj

  

[Catt]

3 hours ago, jimmyjoe said:

 

   I guess my idea of what went on in a small lake during winter and early spring was way too simple. (Can I blame that on river fishing all those years?) 

 

No but you can apply what you learned from river fishing to ponds & lakes.

 

We do a lot of talking on this site about learning bass behavior & that is necessary.

 

The easiest way to learn bass behavior is understanding the ecosystem your fishing.

[NittyGrittyBoy]

@Glenn - that was a good read, thank you for that breakdown. 

 

I'm a river fisherman through and through. I'm constantly in current, and dont have huge balls of shad, herring, etc to follow around. So when I do get an opportunity to fish big lakes, I'm kinda second rate.

 

But, reading material like this and understanding more about bass helps so much. Thanks guys.

[Catt]

Let's expound on this a little further.

 

4 hours ago, Glenn said:

So as temps begin to warm up in Spring, the baitfish head for shallower cover asap for protection

 

This is 100% correct...but only part of the equation. The baitfish are looking for it's food source which is why they're located in this area right here & not that one over yonder.

 

4 hours ago, Glenn said:

 

Sixth, the depth of plant growth is primarily determined by light penetration. As a general rule, the clearer the water, the deeper aquatic vegetation will grow.  Your mileage may vary depending on available nutrients, bottom composition, and type of plants.  But vegetation in 20' or deeper is not uncommon in clear ponds and lakes

 

If we have grass growing at these depths it tells us a lot about the ecosystem.

 

First it says we have a fairly healthy ecosystem.

 

Second it tells us the location of 2 breaks/breaklines, the shallow weedline & the deep weedline. 

[Paul Roberts]

Wow! Great thread.

[frogflogger]

My old mentor said "You'll find bass  where they want to be"

[bazzelite19]

In a shallow lake with max depths of 15 foot then you'll likely find them at the deepest point. But a deeper lake not really so. You can still catch them in less then 10 foot all year long most places. Unless the water is frozen the warmest water isnt necessarily in the deepest water. 39 is the temp you wanna notice. Anything warmer (or cooler between 39 and 32) is actually going to rise because its less dense. So if its not froze the warmer water will actually be toward shallower water, where youll want to hit shallower structure. It goes back to a saying - with winds warmer then the water temp head shallower, with colder winds (or air in general) go deeper.